Watt-Hours (Wh) & Amp-Hours (Ah) Battery Runtime Calculator
Free online Watt-Hours and Amp-Hours Calculator for solar systems, off-grid batteries, RVs, power stations, and electronics. Convert Wh to Ah and Ah to Wh at any voltage (12V, 24V, 48V, 400V). Calculate real-world appliance backup runtime with depth of discharge (DOD) and inverter efficiency losses, plus solar panel recharging time estimates.
Watt-Hours (Wh) & Amp-Hours (Ah) Calculator
Battery Capacity, Wh ⇄ Ah Converter, Runtime Estimator & Solar Sizing
Convert Watt-Hours to Amp-Hours
Electrical Conversion Formulas
Ah = Watt-Hours / Volts
Example: 1200 Wh / 12 V = 100 Ah
Wh = Amp-Hours × Volts
Example: 100 Ah × 12 V = 1200 Wh
Wh = (mAh × Volts) / 1,000
Example: (5,000 mAh × 3.7V) / 1000 = 18.5 Wh
Comprehensive Guide & Calculation Principles: Watt-Hours (Wh) & Amp-Hours (Ah) Battery Runtime Calculator
The Watt-Hours (Wh) & Amp-Hours (Ah) Battery Runtime Calculator delivers precision calculations for chronological time, calendar durations, payroll shift logs, and international timezone coordinates.
Governing Principles of Watt-Hours (Wh) & Amp-Hours (Ah) Battery Runtime Calculator
Time calculations operate on a sexagesimal (base-60) foundation for minutes and seconds, combined with 24-hour solar days and Gregorian calendar algorithms. Accurately tracking intervals requires properly accounting for leap years, variable month lengths (28 to 31 days), timezone offsets, and fractional decimal hours.
Our engine processes all temporal arithmetic client-side with millisecond resolution, ensuring instantaneous and reliable results for personal planning, project management, and payroll compliance.
Step-by-Step Instructions
Select Calculation Mode
Choose whether to calculate Watt-hours (Wh) from Volts and Amp-hours (Ah), Amp-hours from Watt-hours, or battery runtime from appliance wattage.
Enter Electrical Specifications
Input voltage (e.g. 12V, 24V, 48V), capacity (Ah or mAh), and your appliance power consumption in Watts.
Configure Inverter & Depth of Discharge Efficiency
Set battery Depth of Discharge (DoD: 80% for Lead-Acid, 95% for LiFePO4) and inverter conversion efficiency (typically 85%-90%).
Inspect Total Energy & Backup Duration
Review total stored energy in Watt-hours (Wh), Kilowatt-hours (kWh), and estimated backup runtime in hours and minutes.
Key Features & Capabilities
- Comprehensive electrical formula engine: calculates Watt-Hours (`Wh = V * Ah`), Amp-Hours (`Ah = Wh / V`), and Kilowatt-Hours (`kWh = Wh / 1000`)
- Battery runtime calculator modeling real-world appliance loads (refrigerators, CPAP machines, laptops, solar power stations)
- Battery chemistry presets: Lithium Iron Phosphate (LiFePO4 - 95% DoD), NMC Lithium-Ion (90% DoD), and Lead-Acid / AGM (50% DoD)
- Inverter power loss factor integration (85%-95% DC to AC conversion efficiency)
- Solar power generator sizing benchmarks (Jackery, EcoFlow, Bluetti, Anker battery capacities)
- Instant real-time calculation with zero server latency
Frequently Asked Questions
What is the formula to convert Amp-Hours (Ah) to Watt-Hours (Wh)?
The formula is `Watt-Hours (Wh) = Voltage (V) * Amp-Hours (Ah)`. For example, a 12-Volt battery rated at 100 Ah stores `12V * 100Ah = 1,200 Watt-hours (Wh)` of energy (or 1.2 kWh).
How do you calculate how long a battery will power a specific appliance?
The formula for backup runtime is: `Runtime (Hours) = (Battery Capacity in Wh * Depth of Discharge * Inverter Efficiency) / Appliance Wattage`. For example, a 1000Wh LiFePO4 battery (95% DoD) running a 100W TV through an 88% efficient inverter provides `(1000 * 0.95 * 0.88) / 100 = 8.36 hours` of runtime.
What is the difference between milliamp-hours (mAh) and Watt-hours (Wh) for power banks?
Milliamp-hours (mAh) measures electrical charge (`1 Ah = 1000 mAh`), while Watt-hours (Wh) measures true total energy capacity. Smartphone power banks rated at 20,000 mAh operate at an internal cell voltage of 3.7V, which equals `(20,000 / 1000) * 3.7V = 74 Wh` (well within TSA's 100 Wh airline carry-on limit).
Why can't you use 100% of a Lead-Acid battery's rated capacity?
Lead-Acid and AGM batteries suffer permanent sulfation damage and rapid lifespan degradation if discharged below 50% Depth of Discharge (DoD). In contrast, modern Lithium Iron Phosphate (LiFePO4) batteries can safely deliver 90%–95% of their rated capacity without degrading battery health.
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